two-fer: Implement exercise (#740)

* Create README.md file using configlet generate command
* Add exercise with topics to config.json
* Add solution and test case generator
* ran bin/generate command to generate tests

config.json

@@ -886,6 +886,17 @@
         "Logic"
       ]
     },
+    {
+      "uuid": "b02a4214-0f1a-9480-2132-2ea3d5073dbfbec0aa4",
+      "slug": "two-fer",
+      "core": false,
+      "unlocked_by": null,
+      "difficulty": 1,
+      "topics": [
+        "Control-flow (conditionals)",
+        "Strings"
+      ]
+    },
     {
       "uuid": "cae4e000-3aac-41f7-b727-f9cce12d058d",
       "slug": "octal",

exercises/two-fer/.meta/.version

@@ -0,0 +1 @@
+1

exercises/two-fer/.meta/generator/two_fer_case.rb

@@ -0,0 +1,12 @@
+require 'generator/exercise_case'
+
+class TwoFerCase < Generator::ExerciseCase
+
+  def workload
+    if input == nil
+      assert_equal {"TwoFer.two_fer"}
+    else
+      assert_equal { "TwoFer.two_fer(#{input.inspect})" }
+    end
+  end
+end

exercises/two-fer/.meta/solutions/two_fer.rb

@@ -0,0 +1,9 @@
+module BookKeeping
+  VERSION = 1
+end
+
+class TwoFer
+  def self.two_fer(name = 'you')
+    "One for #{name}, one for me."
+  end
+end

exercises/two-fer/README.md

@@ -0,0 +1,69 @@
+# Two Fer
+
+`Two-fer` or `2-fer` is short for two for one. One for you and one for me.
+
+```text
+"One for X, one for me."
+```
+
+When X is a name or "you".
+
+If the given name is "Alice", the result should be "One for Alice, one for me."
+If no name is given, the result should be "One for you, one for me."
+
+## Test-Driven Development
+
+As programmers mature, they eventually want to test their code.
+
+Here at Exercism we simulate [Test-Driven
+Development](http://en.wikipedia.org/wiki/Test-driven_development) (TDD), where
+you write your tests before writing any functionality. The simulation comes in
+the form of a pre-written test suite, which will signal that you have solved
+the problem.
+
+It will also provide you with a safety net to explore other solutions without
+breaking the functionality.
+
+### A typical TDD workflow on Exercism:
+
+1. Run the test file and pick one test that's failing.
+2. Write some code to fix the test you picked.
+3. Re-run the tests to confirm the test is now passing.
+4. Repeat from step 1.
+5. Submit your solution (`exercism submit /path/to/file`)
+
+## Instructions
+
+Submissions are encouraged to be general, within reason. Having said that, it's
+also important not to over-engineer a solution.
+
+It's important to remember that the goal is to make code as expressive and
+readable as we can.
+
+## Running the tests
+
+For running the tests provided, you will need the Minitest gem. Open a terminal window and run the following command to install minitest:
+
+`gem install minitest`
+
+If you would like color output, you can require `'minitest/pride'` in the test file, or note the alternative instruction, below, for running the test file.
+
+In order to run the test, you can run the test file from the exercise directory.
+
+`ruby two_fer_test.rb`
+
+To include color from the command line:
+
+`ruby -r minitest/pride two_fer_test.rb`
+
+## Further information
+
+For more detailed information about the Ruby track, including how to get help if you're having trouble, please visit the exercism.io [Ruby language page](http://exercism.io/languages/ruby/about).
+
+## Source
+
+This is an exercise to introduce users to basic programming constructs, just after hello World. [https://en.wikipedia.org/wiki/Two-fer](https://en.wikipedia.org/wiki/Two-fer)
+
+## Submitting Incomplete Solutions
+
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.

exercises/two-fer/two_fer_test.rb

@@ -0,0 +1,42 @@
+require 'minitest/autorun'
+require_relative 'two_fer'
+
+# Common test data version: 1.1.0 c080bdf
+class TwoFerTest < Minitest::Test
+  def test_no_name_given
+    # skip
+    assert_equal "One for you, one for me.", TwoFer.two_fer
+  end
+
+  def test_a_name_given
+    skip
+    assert_equal "One for Alice, one for me.", TwoFer.two_fer("Alice")
+  end
+
+  def test_another_name_given
+    skip
+    assert_equal "One for Bob, one for me.", TwoFer.two_fer("Bob")
+  end
+
+  # Problems in exercism evolve over time, as we find better ways to ask
+  # questions.
+  # The version number refers to the version of the problem you solved,
+  # not your solution.
+  #
+  # Define a constant named VERSION inside of the top level BookKeeping
+  # module, which may be placed near the end of your file.
+  #
+  # In your file, it will look like this:
+  #
+  # module BookKeeping
+  #   VERSION = 1 # Where the version number matches the one in the test.
+  # end
+  #
+  # If you are curious, read more about constants on RubyDoc:
+  # http://ruby-doc.org/docs/ruby-doc-bundle/UsersGuide/rg/constants.html
+
+  def test_bookkeeping
+    skip
+    assert_equal 1, BookKeeping::VERSION
+  end
+end